1. Field of Invention
This invention generally relates to a medical fluid delivery system. More particularly, this invention relates to a drip chamber that minimizes the formation of air bubbles in a medical fluid delivery system.
2. Description of Related Art
Medical fluid delivery systems are used by medical personnel to inject nutrients and/or medication into a patient's body. "Medical fluid delivery systems," as used herein, include, for example, any system for delivering an intravenous solution such as glucose, saline solution, medical dyes, and medication in fluid form, to a patient. Such systems are used during surgery or when a patient is otherwise unable to ingest nutrients or medication orally.
An intravenous fluid delivery system, for example, generally includes a bag or container of intravenous fluid that is connected through a series of conduits to a needle inserted into a vein in the patient. The bag or container is supported at a higher elevation than the patient so that intravenous fluid flows through the conduits by the force of gravity.
One or more valves are disposed within the system to control the intravenous fluid flow rate. In addition, a drip chamber is disposed in the conduit arrangement between the intravenous fluid bag and the needle to allow medical personnel to visually inspect the "drip" (i.e., flow rate) of intravenous fluid through the system. From the drip rate, the flow rate of the infused fluid can be calculated. The drip chamber also provides a pocket for the collection of air in the system.
In particular, the drip chamber is constructed of a clear material and has a top inlet port connected to the conduit(s) leading to the intravenous fluid bag and a bottom outlet port connected to the conduit(s) leading to the needle. The inlet and outlet ports enclose opposite ends of a generally-cylindrical column, and fluid drips from the inlet downwardly through the column where it collects at the bottom of the column and exists via the outlet.
When infusing fluids intravenously, particularly under pressurized conditions (such as priming the chamber), the infused fluid flows at a high velocity from the drip chamber inlet opening into a pool of fluid contained in the bottom of the drip chamber. As the high velocity fluid impinges the pool surface, the bubbles are entrapped in the fluid pool, thus causing an air-bubble mixture to form. This requires a time-consuming effort to purge the air bubbles from the conduits leading to the patient. If air bubbles are not purged, they may enter the patient and cause an embolism or other harmful effects.
One solution to the problem is proposed in applicant's co-pending application Ser. No. 08/701,874, which is incorporated herein by reference. A member is positioned at an intermediate point within the chamber of the housing and directly in line with the flow path of the intravenous fluid. Under pressurized conditions, the fluid impinges on the member at a high velocity. The member effectively reduces the velocity of the fluid, thereby minimizing bubbles in the intravenous fluid pool. The member is attached to the side wall of the housing, which may, in some instances, increase manufacturing time and costs.